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arXiv · 0905.4689

Light scalar mesons: comments on their behavior in the 1/Nc expansion near Nc=3 versus the Nc --> infinity limit

J. R. Pelaez·G. Rios
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Abstract

We briefly review how light meson resonances are described within one and two-loop Unitarized Chiral Perturbation Theory amplitudes and how, close to Nc=3, light vectors follow the Nc behavior of $q\bar q$ mesons whereas light scalars do not. This supports the hypothesis that the lightest scalar is not predominantly a $q\bar q$ meson, although a subdominant $q\bar q$ component is suggested around 1 GeV at somewhat larger Nc. In contrast, when Nc is very far from 3, like in the Nc --> infinity limit, we explain again in detail why unitarization is not, a priori, reliable nor robust and why this limit should not be used to drag any conclusions about the dominant nature of physical light scalar mesons.

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J. R. Pelaez, G. Rios. 2009-05-28. Light scalar mesons: comments on their behavior in the 1/Nc expansion near Nc=3 versus the Nc --> infinity limit. https://arxiv.org/abs/0905.4689

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